Mechanical seat recline lock mechanism with integrated damping

ABSTRACT

A mechanical seat recline lock mechanism that employs a lead screw device to backdrive a nut and disk. The disk is held in place by a spring-loaded friction pin when motion needs to be constrained. The rotating disk can be oiled or greased to provide damping action.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

COPYRIGHTED MATERIAL

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lock mechanism for controlling seatrecline function for passenger comfort. More specifically, the inventionrelates to a lock mechanism for controlling seat recline function thatprovides nearly infinite position options and incorporates integrateddamping.

2. Related Art

The recline function for seat backs in the aircraft and automotiveindustry has been a standard for many years. The two industries haveapproached the solution from different perspectives. The automotiveindustry has traditionally used a mechanical locking device thatpositively locks the seat back into a position by means of a spring andgear type engagement. This arrangement is adequate for the normalautomotive application where the seat back is not adjusted very manytimes over the life of the product. However, it does not allow forpositive engagement until the teeth are properly aligned, and therefore,results in substantial wear due to the high forces encountered when theteeth are forced to engage.

The aircraft industry has a different need due to a different useprofile. An aircraft seat recline function is activated at least twiceper flight (take-off and landing) and potentially several times inflight with meals, reading, sleeping, etc. The solution implementedapproximately 40 years ago was a hydraulic cylinder with a bypass portcontrolled by a lever. The cylinder piston separates two oil-filledchambers connected by a valve that allows oil to pass when activated,thereby allowing motion of the piston shaft. This arrangement has manyattractive features, including nearly infinite hold power, motiondamping, and a small package. However, it also has disadvantages such asa propensity for leaks (internal and external), relatively heavy weight,and high cost. Aircraft-type hydraulic systems tend to leak because theyare based on pressurized hydraulic fluid with tight tolerances (typicalof hydraulic systems) on the internal dimensions to operate properly.Once these tolerances begin to wear, the performance of the devicedeteriorates rapidly.

It is to the solution of these and other problems that the presentinvention is directed.

SUMMARY OF THE INVENTION

It is accordingly a primary object of the present invention to provide aseat recline lock mechanism that is mechanical and has infiniteadjustability.

It is another object of the present invention to provide a seat reclinelock mechanism that is mechanical and has integral damping.

It is another object of the present invention to provide a seat reclinelock mechanism that is mechanical and has a long life.

It is still another object of the present invention to provide a seatrecline lock mechanism is mechanical and that does not leak.

It is still another object of the present invention to provide a seatrecline lock mechanism is mechanical and light in weight.

These and other objects are achieved by a mechanical seat recline lockmechanism that employs a lead screw device to backdrive a nut and disk.The disk is held in place by a spring-loaded friction pin when motionneeds to be constrained. The rotating disk can be oiled or greased toprovide damping action.

Unlike prior art mechanical devices, the mechanical seat recline lockmechanism in accordance with the present invention is its infiniteadjustability, integral damping, and longer life. In contrast to priorart hydraulic systems, the mechanical seat recline lock mechanism inaccordance with the present invention does not leak and has a lighterweight.

Other objects, features, and advantages of the present invention will beapparent to those skilled in the art upon a reading of thisspecification including the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is better understood by reading the following DetailedDescription of the Preferred Embodiments with reference to theaccompanying drawing figures, in which like reference numerals refer tolike elements throughout, and in which:

FIG. 1 is a perspective view of a seat recline lock mechanism inaccordance with the present invention.

FIG. 2 is a side elevational view of the seat recline lock mechanism ofFIG. 1.

FIG. 2A is a partial side elevational view of an alternative headconfiguration of the lead screw as shown in FIG. 2.

FIG. 3 is a cross-sectional view of the seat recline lock mechanism asshown in FIG. 2.

FIG. 4 is an exploded perspective view of the seat recline lockmechanism of FIG. 1.

FIG. 5 is a front view of the seat recline lock mechanism of FIG. 1.

FIG. 6 is a back view of the seat recline lock mechanism of FIG. 1.

FIG. 7 is a perspective view of a first type of seat in which themechanical seat recline lock mechanism of the present invention ismounted, with the seat back in the upright position.

FIG. 8 is an enlarged, partial perspective view of the mounting of themechanical seat recline lock mechanism as shown in FIG. 7.

FIG. 9 is a side elevational view of a second type of seat in which themechanical seat recline lock mechanism of the present invention ismounted, with the seat back in the upright position.

FIG. 10 is a side elevational view of the seat and mechanical seatrecline lock mechanism of FIG. 9, with the seat back in a recliningposition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In describing preferred embodiments of the present invention illustratedin the drawings, specific terminology is employed for the sake ofclarity. However, the invention is not intended to be limited to thespecific terminology so selected, and it is to be understood that eachspecific element includes all technical equivalents that operate in asimilar manner to accomplish a similar purpose.

Referring now to FIGS. 1-6, the mechanical seat recline lock mechanism100 in accordance with the present invention comprises anexternally-threaded lead screw 10 having a shaft 10 a and a head 10 b,an internally-threaded lead screw nut 20 threadably engaging the leadscrew 10, and an annular brake disk 30 concentric with and matinglyengaging the perimeter of the lead screw nut 20. The head 10 b providesan interface to the seat. The specific configuration of the head 10 bdepends upon the specifics of the interface, and is not considered to bea novel feature of the present invention. An alternative configurationof the head 10 b is shown in FIG. 2A.

An annular bearing 40 comprising an annular race 40 a with a pluralityof ball bearings 40 b is positioned on either side of the brake disk 30.A housing 50 is configured with a housing inner cavity that encases thelead screw nut 20, the brake disk 30, and the bearings 40, the housinginner cavity being sized to provide a small clearance between the brakedisk 30 and the housing 50, into which oil is introduced during theassembly process, for a purpose to be described hereinafter. In order toprevent leakage of the oil from between the two parts 50 a and 50 b, agasket or O-ring 60 can be provided between the two parts 50 a and 50 b.

The bearings 40 perform two functions, (1) constraining the lead screwnut 20 to the housing 50 against axial forces applied to the lead screw10, and (2) providing low friction radial support of the lead screw nut20 to the housing 50.

The housing 50 can be formed in two parts, a first part 50 a and asecond part 50 b, for ease in manufacture and assembly. The first andsecond parts 50 a and 50 b define the housing inner cavity that receivesthe lead screw nut 20, the brake disk 30, and the bearing races. Inorder to reduce the weight of the housing 50, grooves 52 can be formedin the outer face of the first part 50 a. Strengthening ribs 54 areformed on the outer face of the second part 50 b. Because the housing 50is formed of a lightweight material (examples of which include, but arenot limited to aluminum, titanium, magnesium, and plastic), the ribs 54strengthen the housing 50 when the mechanism 100 is locked andconstraining linear forces. As will be appreciated by those of skill inthe art, other means besides the ribs 54 can be used to addressmechanical loads.

An actuation lever 70 is pivotably mounted to the outer face of thefirst part 50 a of the housing 50 (via, for example, a pin 72) so as todefine a fulcrum 70 a (which is coincident with the longitudinal axis ofthe pin 72), an effort arm 70 b, and a resistance arm 70 c. A spring 80is connected at one of its ends to the effort arm 70 b of the actuationlever 70 and at the other of its ends is seated in an aperture 56 in theouter face of the first part 50 a of the housing 50 to bias the effortarm 70 b away from the housing 50, and thus to bias the resistance arm70 c towards the housing 50 and the brake disk 30. A resistance pin 90is inserted into and extends through an aperture 58 in the first part 50a of the housing 50 between the resistance arm 70 c of the actuationlever 70 and the brake disk 30, so as to contact the brake disk 30 atits outer circumference.

The primary mechanical support is concentrated in the shaft 10 b andhighly concentrated in the housing 50. The lead screw 10 is used to backdrive the nut 20, which in turn rotates the disk 30. The disk 30 iscaptured between the two halves of the housing 50 with a smallclearance. The oil in the clearance between the housing 50 and the disk30 acts on the disk 30 in shear to provide a damping action. The pin 90,which has force from the spring 80 applied through the actuation lever70, contacts the brake disk 30 so as to prevent its rotation, providingthe locking action. When the effort arm 70 b of the actuation lever 70is moved towards the housing 50, either directly or through a cable, theforce is removed from the pin 90, which allows the disk 30 to rotate,and therefore, allows the shaft 10 b of the lead screw 10 to movelinearly through the seat recline lock mechanism 100, and moreparticularly, through the lead screw nut 20.

Referring now to FIGS. 7 and 8, there is shown a first type of seat 200in which the mechanical seat recline lock mechanism 100 of the presentinvention is mounted. The seat 200 comprises a seat pan 210, a seat panframe 212 extending from the back of the seat pan 210, a seat back 220,and a seat back frame 222 extending from the bottom of the seat back220, the seat back frame 222 being pivotably mounted to the seat panframe 212 to permit the seat back 220 to recline relative to the seatpan 210. The housing 50 of the mechanical seat recline lock mechanism100 is fixedly mounted to a bracket 214 extending downwardly from thebottom of the seat pan 210, while the head 10 b of the lead screw 10threadably engages a bracket 224 fixedly mounted to the seat back frame222. The brackets 214 and 224 are positioned along one side of the seat200 so that the mechanical seat recline lock mechanism 100 is easilyaccessible to the person sitting in the seat 200. Operation of themechanical seat recline lock mechanism 100 results in reclining motionof the seat back 220 as indicated by the arrow A1.

Referring now to FIGS. 9 and 10, there is shown a second type of seat200′ in which the mechanical seat recline lock mechanism 100 of thepresent invention is mounted. The seat 200′ comprises a seat pan 210, aseat pan frame 212′ extending from the back of the seat pan 210, a seatback 220, and a seat back frame 222′ extending from the bottom of theseat back 220. The seat pan 210 is slidably mounted in fixed left andright tracks 230 via front and back rollers 240 a and 240 b, and theseat back frame 222 is pivotably mounted to the seat pan frame 212 inalignment with the back rollers 240 b. A pair of struts 250 on eitherside of the seat 200′ are pivotably connected at one end to the seatback 220 and at the other end to the back ends of the tracks 230. Theleft and right tracks 230 are themselves mounted to a fixed base 250.The housing 50 of the mechanical seat recline lock mechanism 100 isfixedly mounted to a bracket 214 extending downwardly from the bottom ofthe seat pan 210, while the head 10 b of the lead screw 10 threadablyengages a bracket 264 fixedly mounted to the base 260. As with the firsttype of seat 200, the brackets 214 and 264 are positioned along one sideof the seat 200′ so that the mechanical seat recline lock mechanism 100is easily accessible to the person sitting in the seat 200′. Operationof the mechanical seat recline lock mechanism 100 results both inreclining motion of the seat back 220 as indicated by the arrow A1 andforward and backward motion of the seat pan 210 as indicated by thearrow A2.

The basic principles upon which the seat recline lock mechanism 100 isconstructed allow it to be designed and built with: (1) any variation ofgear reduction between the lead screw 10 and the lead screw nut 20, aslong as it can be back driven; (2) any multiple of brake disks 30 andspring 80/lever 70 combinations to provide normal forces and frictionadequate to hold the brake disk 30, and thereby hold the nut 20 to whichit is matingly engaged, from rotating; (3) any viscosity of oil to varydamping characteristics; (4) a barrel type configurations for thehousing 50 for lower profile construction; and (5) any means that canreplace the lead screw 10/lead screw nut 20 combination to transformmotion from linear to rotational, including, but not limited to spurgears, rack and pinion gears, planetary gear set, and chain andsprockets, all of which are also capable of being back driven.

Because the seat recline lock mechanism 100 is a friction-based device,there are no gear teeth to wear away, and there is no harsh “locking”action. The seat recline lock mechanism 100 also provides infiniteadjustability, as well as integrated damping due to shear of the oil inthe lock mechanism acting on the disk 30.

Further, the seat recline lock mechanism 100 is not under pressure orrequired to constrain oil under pressure, thereby preventing theoccurrence of leaks. The internal tolerances are much less critical thanin a hydraulic system. It weighs less than a conventional hydraulic locksystem because it only requires a few drops of oil compared toapproximately 100 mL in the conventional hydraulic lock system.

Modifications and variations of the above-described embodiments of thepresent invention are possible, as appreciated by those skilled in theart in light of the above teachings. It is therefore to be understoodthat, within the scope of the appended claims and their equivalents, theinvention may be practiced otherwise than as specifically described.

1. A mechanical seat recline lock mechanism for a reclining seat,comprising: motion-transforming means for transforming linear motion torotational motion, the motion-transforming means including an interfaceto the reclining seat; at least one brake disk rotationally driven bythe motion-transforming means; damping means for providing a dampingaction to the at least one brake disk; and holding means for selectivelyapplying normal forces and friction adequate to hold the at least onebrake disk and thereby preventing the motion-transforming means fromrotating.
 2. The mechanical seat recline lock mechanism of claim 1,wherein the motion-transforming means comprises a back-drivable,externally-threaded lead screw and an internally-threaded lead screw nutthreadably engaging the lead screw.
 3. The mechanical seat recline lockmechanism of claim 2, wherein the at least one brake disk is an annularbrake disk concentric with and matingly engaging the perimeter of thelead screw.
 4. The mechanical seat recline lock mechanism of claim 1,further comprising a housing configured with a housing inner cavityencasing the at least one brake disk, the housing inner cavity beingsized to provide a clearance between the brake disk and the housing, andwherein the damping means comprises oil within the cavity.
 5. Themechanical seat recline lock mechanism of claim 1, wherein the holdingmeans comprises: a pivotable actuation lever having an effort arm and aresistance arm; a resistance pin positioned between the resistance armand the at least one brake disk so as to contact the at least one brakedisk at the outer circumference thereof; and means for biasing theresistance arm towards the at least one brake disk.
 6. The mechanicalseat recline lock mechanism of claim 5, further comprising a housingconfigured with a housing inner cavity encasing the at least one brakedisk and an aperture therein for receiving the resistance pin, andwherein the actuation lever is pivotably mounted on an outer face of thehousing.
 7. A mechanical seat recline lock mechanism for a recliningseat, comprising: an externally-threaded lead screw and a back-drivable,internally-threaded lead screw nut threadably engaging the lead screwfor transforming linear motion to rotational motion, the lead screwincluding an interface to the reclining seat; at least one brake diskrotationally driven by the lead screw nut; damping means for providing adamping action to the at least one brake disk; and holding means forselectively applying normal forces and friction adequate to hold the atleast one brake disk and thereby prevent rotation of the lead screw nut.8. The mechanical seat recline lock mechanism of claim 7, wherein the atleast one brake disk is an annular brake disk concentric with andmatingly engaging the perimeter of the lead screw.
 9. The mechanicalseat recline lock mechanism of claim 7, further comprising a housingconfigured with a housing inner cavity encasing the at least one brakedisk, the housing inner cavity being sized to provide a clearancebetween the brake disk and the housing, and wherein the damping meanscomprises oil within the cavity.
 10. The mechanical seat recline lockmechanism of claim 7, wherein the holding means comprises: a pivotableactuation lever having an effort arm and a resistance arm; a resistancepin positioned between the resistance arm and the at least one brakedisk so as to contact the at least one brake disk at the outercircumference thereof; and means for biasing the resistance arm towardsthe at least one brake disk.
 11. The mechanical seat recline lockmechanism of claim 10, further comprising a housing configured with ahousing inner cavity encasing the at least one brake disk and anaperture therein for receiving the resistance pin, and wherein theactuation lever is pivotably mounted on an outer face of the housing.12. A mechanical seat recline lock mechanism for a reclining seat,comprising: an externally-threaded lead screw and a back-drivable,internally-threaded lead screw nut threadably engaging the lead screwfor transforming linear motion to rotational motion, the lead screwincluding an interface to the reclining seat; at least one brake diskrotationally driven by the lead screw nut; a housing configured with ahousing inner cavity encasing the at least one brake disk, the housinginner cavity being sized to provide a clearance between the brake diskand the housing; oil within the cavity for providing a damping action tothe at least one brake disk; a pivotable actuation lever pivotablymounted on an outer face of the housing, the actuation lever having aneffort arm and a resistance arm; a resistance pin positioned between theresistance arm and the at least one brake disk so as to contact the atleast one brake disk at the outer circumference thereof; and means forbiasing the resistance arm towards the at least one brake disk holdingmeans for selectively applying normal forces and friction adequate tohold the at least one brake disk and thereby prevent rotation of thelead screw nut.
 13. The mechanical seat recline lock mechanism of claim12, wherein the at least one brake disk is an annular brake diskconcentric with and matingly engaging the perimeter of the lead screw.14. The mechanical seat recline lock mechanism of claim 12, wherein thehousing includes an aperture therein and the resistance pin extendsthrough the aperture.